We propose to investigate the structural instability of five proteolytic fragments of myosin as induced by temperature. These studies will follow thermal transition by measurement of circular dichroism spectra and by a pH method. Hydrodynamic methods will also be used. BIBIOGRAPHIC REFERENCES: A mathematical Method for Temperature Compensation of pH Measurements. Charles C. Goodno, Charles A. Swenson and Henry B. Bull, Analytical Biochem. 67, 220 (1975). On Enthalpy of Binding ADP to Heavy Meromyosin, Charles C. Goodno and Charles A. Swenson, J. Supra. Molecular Structure, 4, (1975).